P1637 Smart Alternator Faults Sensor/Circuit Malfunction

How to Diagnose and Solve P1637 Smart Alternator Faults Sensor/Circuit Malfunction Issues


Ever been stuck on the road with a car that won’t start? It’s a frustrating experience, especially when you can’t figure out what’s wrong. One common issue that can cause this is a P1637 Smart Alternator Faults Sensor/Circuit Malfunction. But don’t worry, I’m here to help you diagnose and solve this problem.

Understanding the P1637 Code

First things first, let’s understand what the P1637 code means. This code indicates a problem with the alternator’s voltage output. The alternator is a crucial component of your car’s electrical system, and any malfunction can lead to serious issues.

What is a Smart Alternator?

A smart alternator is an advanced version of the traditional alternator. It’s designed to improve fuel efficiency and reduce emissions by adjusting its output based on the vehicle’s electrical needs.

Common Symptoms of P1637 Smart Alternator Faults

Knowing the symptoms of a P1637 Smart Alternator Fault can help you diagnose the problem early. These symptoms include:

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– Difficulty starting the car
– Dimming or flickering lights
– Battery warning light on the dashboard
– Reduced battery life

Diagnosing P1637 Smart Alternator Faults

Now that we know the symptoms, let’s move on to diagnosing the problem. Here’s a step-by-step guide:

Step 1: Check the Battery

The first step is to check the battery. A faulty battery can cause the alternator to overwork, leading to a P1637 code.

Step 2: Inspect the Alternator

Next, inspect the alternator for any visible damage. Look for signs of wear and tear, such as frayed wires or corrosion.

Step 3: Test the Alternator

If the battery and alternator look fine, the next step is to test the alternator. You can do this using a multimeter.

Solving P1637 Smart Alternator Faults

Once you’ve diagnosed the problem, it’s time to solve it. Here’s how:

Step 1: Replace the Battery

If the battery is the issue, replace it with a new one. Make sure to choose a battery that’s compatible with your vehicle.

Step 2: Repair or Replace the Alternator

If the alternator is the problem, you may need to repair or replace it. If you’re not comfortable doing this yourself, consider taking your car to a professional mechanic.

Step 3: Reset the Code

After fixing the issue, you’ll need to reset the P1637 code. You can do this using an OBD-II scanner.


Dealing with a P1637 Smart Alternator Faults Sensor/Circuit Malfunction can be a daunting task, but with the right knowledge and tools, you can diagnose and solve this problem yourself. Remember, regular maintenance is key to preventing such issues in the future.


1. What causes a P1637 Smart Alternator Fault?

A P1637 fault is usually caused by a malfunctioning alternator or battery. Other causes can include a faulty voltage regulator or wiring issues.

2. Can I drive my car with a P1637 code?

While it’s possible to drive with a P1637 code, it’s not recommended. This code indicates a serious issue with your car’s electrical system, which can lead to other problems if not addressed.

3. How much does it cost to fix a P1637 Smart Alternator Fault?

The cost to fix a P1637 fault can vary depending on the cause. Replacing a battery can cost around $100-$200, while replacing an alternator can cost $300-$500.